The present invention relates to forward-looking infared (FLIR) detector systems of the type in which the video display is electro-optically multiplexed to an infared detector by a video scanner optically coupled to a light-emitting array which is responsive to the infared detector. Specifically, the invention relates to means for testing the video chain of such a system without energization of the infared detector.
In the prior art, one type of FLIR system utilizes an infared detector array, for detecting infared energy emanating from a scene, and a light-emitting array, such as an array of LED's, coupled to the detector array to produce a visible image of the detected scene. A line-scanning electro-optical multiplexer receives light focused by coupling optics from the light-emitting array and ultimately drives a video display, such as a CRT. Heretofore, it has been necessary to energize the entire FLIR system to test the video chain. This is extremely time-consuming because the infared detectors are cryogenically cooled and require a long "cool-down" period before reaching a stable operating condition. The principal object of the present invention is to provide a means of testing the video chain of a FLIR system without requiring start-up or operation of the cryogenically-cooled infared detector array.